The present invention relates to a method and apparatus for use in the performance of ankle arthroscopy procedures and, more particularly, to an improved system for providing non-invasive ankle joint distraction in support of arthroscopic procedures.
As described in my prior U.S. Pat. No. 5,063,918, it is usually necessary to provide some form of ankle joint distraction in order to create sufficient space in the joint for the arthroscope and various other surgical equipment and instruments used in ankle arthroscopy. Furthermore, the degree of distraction will vary depending on the nature of the procedure, the type and size of surgical instruments required, and the relative tightness or looseness of the joint in a particular patient. The method and apparatus in the above patent provides for the use of a basic non-invasive technique and, if the level of distraction it provides is insufficient, the ability to convert without interruption to an invasive distraction technique utilizing pinned connections between the bones of the lower leg and foot.
Relatively recent improvements in the design and construction of arthroscopic instruments include smaller size instruments requiring less space within the joint for adequate performance. In turn, the amount of ankle joint distraction may also be reduced in many cases. As a result, the importance of non-invasive distraction techniques has recently taken on somewhat greater importance relative to invasive techniques. This is also significant because the disadvantages and potential complications of invasive techniques are well documented and these techniques are only utilized when adequate distraction by non-invasive means cannot be attained.
One method of providing non-invasive ankle distraction is shown in U.S. Pat. No. 5,020,525. In this method, a removable strap is attached to the patient's foot and the opposite end of the strap is strung to an outrigger fixed to and extending several feet away from the foot of the operating table. Variable distraction force is applied in a direction generally axially of the patient's leg with a manually operated crank and pulley system. The method provides good distraction and the ability to control the amount of the distraction force. However, the horizontal position of the leg and foot results in difficult access to posterior portals of the ankle and also results in the problem of water or saline solution running down the arthroscope and into the camera. The outrigger mechanism may also create an obstacle to the surgeon. Finally, the need to convert to invasive distraction means requires complete repositioning of the patient which is cumbersome and time consuming.
In another known method, the patient is positioned supine at the end of the operating, table with the hip and knee flexed and the lower leg depending downwardly from the end of the table over a padded horizontal bar behind the knee. Distraction of the ankle joint is provided by pulling vertically downward on a strap attached to the foot of the patient and secured to a pivotal cantilevered arm below the table. This method does not offer much variation in position and requires careful attention to the potential circulatory problems attendant the application of pressure to the popliteal area with the knee acutely flexed over the padded bar.
My prior U.S. Pat. No. 5,063,918 describes a non-invasive distraction technique which allows variable positioning of the ankle above the operating table to accommodate access to the ankle joint from any direction. The non-invasive methods disclosed in this patent utilize an adjustable distraction device attached between the foot of the patient and the Clark rail on the operating table to provide a variable level of joint distraction. However, two deficiencies in the method disclosed in this patent have been noted. First, the initial positioning of the distraction device by sliding it along the Clark rail and clamping it in position locates the patient's foot and ankle fairly close to the operating table, thereby somewhat inhibiting access, particularly when the leg is only slightly flexed. Second, the overall range of adjustment of the height of the ankle with respect to the top of the operating table is somewhat limited, making access inconvenient or troublesome for some surgeons and for the techniques they may wish to utilize.